We will test the specific hypothesis that those narcotic drugs that have "addiction" liability will all lower the threshold for intracranial self-stimulation. Mixed agonist-antagonist like nalorphine that has little or no addiction liability will not lower the threshold. Agonist-antagonist that have "addiction liability", like pentazocine, will lower the threshold. As a corollary to studies in which we determine the threshold for positive reward we will study the threshold for intracranial stimulation in aversive areas of the brain. We will study these effects in areas of the brain that are predominately dopaminergic (substantia nigra), predominately noradrenergic (locus coeruleus) and mixed (medial forebrain bundle). In addition to the narcotic analgesics we will continue our cocaine studies by determining the effect in brain areas other than the MFB. If time permits, we will also look at other drugs such as the barbiturates, the anxiolytic and neuroleptic drugs. We will continue to explosure the effects of PCP on the foot-shock titration procedure to determine if the methods we are using are appropriate models for the action of this drug in man.